The liquid crystal display (LCD) devices may be generally classified into transmission type liquid crystal display device and reflective type liquid crystal display device. The transmission type LCD device has a backlight as light source therein (or referred to backlight source). The reflective type LCD device has a reflective film therein, the reflective film functions as a light source by reflecting the external light incident into the LCD device. The reflective type LCD device has the advantages of lower power consumption, lighter weight and thinner thickness due to there is no backlight source. On the other hand, the transmission type LCD device can display well in dark environments because it has a light source therein.
The transmission type LCD device also has advantages of displaying with high brightness and high contrast, because it displays using the light from the backlight source and is not affected by ambient light, however the backlight source may cause more power consumption. Moreover, in a very bright environment, such as outdoor in a sunny day, lower resolution or the further increase power consumption resulted by maintaining the resolution through increasing the brightness of the backlight source may occur in the transmission type LCD device.
The reflective type LCD device has the advantages of extremely low power consumption due to it has no backlight source, however its displaying brightness and contrast is significantly impacted by operation environment such as the ambient brightness. Especially, the reflective type LCD device has the disadvantages of extremely low resolution in a dark operation environment.
Nowadays, there is a kind of LCD device called transflective LCD device which has the advantages of both the reflective type LCD device and the transmission type LCD device. In one pixel region of the transflective type LCD device, there are a reflective pixel electrode used to reflect the light from the environment and a transmission pixel electrode used to transmit the light from the backlight source, so that switching between the transmission display mode and the reflective display mode can be operated according to various operation environments, or display can be perform in both modes at the same time. Therefore, the transflective LCD device has both the advantage of lower power consumption of the reflective type LCD device, and less affect by ambient brightness and display in high brightness and high contrast of the transmission type LCD device. Also, the disadvantage of the resolution reduction of the transflective LCD device in a very bright environment, such as outdoor in a sunny day, can be effectively depressed.
In the prior art, an In Plane Switching (IPS) display mode technology has been proposed in order to improve the viewing angle properties of the liquid crystal cell. FIG. 1 shows an exiting LCD device adopting IPS display mode. The LCD device includes an upper glass substrate 101, a lower glass substrate 102, a transparent comb-shaped tin indium oxide (ITO) electrode 103 attached to the lower glass substrate 102 and located corresponding to a transmission region, and a liquid crystal layer 104 sandwiched between the upper glass substrate 101 and the lower glass substrate 102. A lateral electric field parallel to the substrates is generated by applying a voltage to the comb-shaped ITO electrode 103, so that the liquid crystal molecules rotate in a plane parallel to the substrates under the effect of the electric field and the LCD display the images and obtain a wider viewing angle.
For the transflective LCD device adopting IPS mode, in order to make the electro-optic curves of the transmission regions and the reflective regions consistent, an organic film is typically provided in the reflective regions of the transflective LCD device, wherein the thickness of the organic film is set, so that the thickness of the liquid crystal layer in the reflective regions is half of that in the transmission regions. Therefore, comb-shaped electrodes need to be made in the transmission regions and the reflective regions respectively, which increases the process difficulty, and impacts on the yield rate largely. If the transflective LCD device adopting IPS display mode is made to be a single cell gap, in order to make the electro-optic curves of the transmission regions and the reflective regions consistent, it is necessary to control the transmission regions and the reflective regions, respectively, and thus two thin film transistors (TFT) must be used, which increases the process difficulty and the cost of the product.
In view of the problems above, it is intended to provide a transreflective LCD device without a dual cell gap or two TFTs for the transmission regions and the reflective regions respectively, which can be switched between various modes depending on different intensities of the environment light, and thus the process will be simplified and the cost will be reduced.